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| After retrieving the block from the freezer, I massed it on a gram scale. Since the procedure was done in two days, I split up the data into two groups: Day 1 and Day 2. Day one and two data of the mass of the chunks here The data is not really dynamic, but it does show pretty much how consistent the masses of the ice chunks were. Uncertainty was measures in this chart when the ice chunks appeared to gain weight. Since I did not do anything to aid them in gaining weight, it was purely an error on the part of the scale. I also weighed the mass of the sand plus the cup: Day one and two data of the mass of the sand/cup here As one can see, I ran into some troubles, because of the numbers dancing about. The results, so far, are proving my hypothesis wrong. It is very convenient, though, that both days match a pattern. The next step is to find the applied forces and the natural forces. To come up with the applied force, or the frictional force, I used the equation Ffr=mg. This means, that I took the mass of the sand and multiplied it with the gravitational constant, 9.8 m/s² . I did that for all of the grades. Next, to get the natural force, I used the formula Fn=mg. M= the mass of the ice chunk and g is once again the gravitational constant. I also did that for the six different grades in this chart for both days: Day one and two data of the applied and natural forces here The next chart is finally what I have been searching for, m . To get m , first I used the equation Ffr=Fnm to find m . I just simply took the applied force and divided it by the natural force. m must be less than zero to be true. If it isn’t, part of the data is incorrect. Fortunately, my coefficients of friction are always below zero. The following charts and graphs prove this:
Day one and two data of the coefficients of friction here This graph is only from the first day, but as one can see, it definitely shows a very distinctive pattern. Notice that the coefficient of friction is high on the lower grades of sandpaper, but the coefficient drops in the middle ranges. It finishes up having a higher coefficient of friction than the middle grades and almost equal to the lowest grade. Here is the graph of the second day: Here again do we see the reoccurring "v" shape. Since I figured after the first day that by reversing the method, the ice would act differently on the higher grades and the lower grades. Except for a few rare occurrences, the results show that the second procedure did not change greatly. It really comes together when both days are on the same graph, for example:
On this graph, it is clearly noticeable that each line has a "dip" in it. This usually happened around the 150 or the 220 grit. This graph concludes that really low and high grades of sandpaper are fairly high friction surfaces and the medium grades are lower friction surface. Again, it goes against my hypothesis, but why? |
